Differential involvement of ezrin/radixin/moesin proteins in sphingosine 1-phosphate-induced human pulmonary endothelial cell barrier enhancement.

TitleDifferential involvement of ezrin/radixin/moesin proteins in sphingosine 1-phosphate-induced human pulmonary endothelial cell barrier enhancement.
Publication TypeJournal Article
Year of Publication2011
AuthorsAdyshev DM, Moldobaeva NK, Elangovan VR, Garcia JGN, Dudek SM
JournalCell Signal
Volume23
Issue12
Pagination2086-96
Date Published2011 Dec
ISSN Number1873-3913
KeywordsActins, Amides, Antigens, CD, Bacterial Proteins, Bacterial Toxins, Cadherins, Cell Membrane, Cells, Cultured, Chelating Agents, Cytoskeletal Proteins, Cytoskeleton, Egtazic Acid, Electric Impedance, Endothelial Cells, Gene Knockdown Techniques, Humans, Imidazoles, Lysophospholipids, Membrane Proteins, Microfilament Proteins, Oxadiazoles, p38 Mitogen-Activated Protein Kinases, Permeability, Phosphorylation, Protein Kinase C, Pulmonary Artery, Pyridines, Receptors, Lysosphingolipid, rho GTP-Binding Proteins, rho-Associated Kinases, RNA Interference, Sphingosine, Thiophenes
Abstract

<p>Endothelial cell (EC) barrier dysfunction induced by inflammatory agonists is a frequent pathophysiologic event in multiple diseases. The platelet-derived phospholipid sphingosine-1 phosphate (S1P) reverses this dysfunction by potently enhancing the EC barrier through a process involving Rac GTPase-dependent cortical actin rearrangement as an integral step. In this study we explored the role of the ezrin, radixin, and moesin (ERM) family of actin-binding linker protein in modulating S1P-induced human pulmonary EC barrier enhancement. S1P induces ERM translocation to the EC periphery and promotes ERM phosphorylation on a critical threonine residue (Ezrin-567, Radixin-564, Moesin-558). This phosphorylation is dependent on activation of PKC isoforms and Rac1. The majority of ERM phosphorylation on these critical threonine residues after S1P occurs in moesin and ezrin. Baseline radixin phosphorylation is higher than in the other two ERM proteins but does not increase after S1P. S1P-induced moesin and ezrin threonine phosphorylation is not mediated by the barrier enhancing receptor S1PR1 because siRNA downregulation of S1PR1 fails to inhibit these phosphorylation events, while stimulation of EC with the S1PR1-specific agonist SEW2871 fails to induce these phosphorylation events. Silencing of either all ERM proteins or radixin alone (but not moesin alone) reduced S1P-induced Rac1 activation and phosphorylation of the downstream Rac1 effector PAK1. Radixin siRNA alone, or combined siRNA for all three ERM proteins, dramatically attenuates S1P-induced EC barrier enhancement (measured by transendothelial electrical resistance (TER), peripheral accumulation of di-phospho-MLC, and cortical cytoskeletal rearrangement. In contrast, moesin depletion has the opposite effects on these parameters. Ezrin silencing partially attenuates S1P-induced EC barrier enhancement and cytoskeletal changes. Thus, despite structural similarities and reported functional redundancy, the ERM proteins differentially modulate S1P-induced alterations in lung EC cytoskeleton and permeability. These results suggest that ERM activation is an important regulatory event in EC barrier responses to S1P.</p>

DOI10.1016/j.cellsig.2011.08.003
Alternate JournalCell. Signal.
PubMed ID21864676
PubMed Central IDPMC3651873
Grant ListP01 HL058064-15 / HL / NHLBI NIH HHS / United States
R01 HL088144-03 / HL / NHLBI NIH HHS / United States
R56 HL088144 / HL / NHLBI NIH HHS / United States
P01 HL058064-13 / HL / NHLBI NIH HHS / United States
HL088144 / HL / NHLBI NIH HHS / United States
HL058064 / HL / NHLBI NIH HHS / United States
R01 HL088144 / HL / NHLBI NIH HHS / United States
P01 HL058064-14 / HL / NHLBI NIH HHS / United States
P01 HL058064 / HL / NHLBI NIH HHS / United States